NEWS RELEASE: Osisko Mining Provides Quebec Exploration Update (February 8, 2018)

Exploration Budget for 2018: $100 million

(Toronto, February 8, 2018) Osisko Mining Inc. (OSK:TSX) (“Osisko” or the “Corporation”) is pleased to provide an update on the progress of exploration at its 100% owned Windfall Lake, Urban Barry and Quévillon gold projects located in the Abitibi greenstone belt, Eeyou Istchee James Bay, Québec.

Osisko has been conducting new exploration and definition drilling at Windfall for 26 months, since late October 2015. As of the end of January 2018, Osisko has completed 518,000 metres of the planned 800,000 metres to complement the pre-existing 180,000 metres drilled at Windfall by previous operators.

The company is rapidly advancing the Windfall and Lynx deposits through a balance of resource delineation drilling and exploration drilling for extensions and new mineralized zones. Osisko has been successful in the past two years at significantly expanding the known areas of mineralization in the Windfall system and reinterpreting the geological model of the Windfall deposit.

Drilling over the past 18 months has been directed by the evolving intrusion-related geological model, leading to the discovery of significant extensions of the previously known mineralized zones, and to the discovery of the new Lynx deposit, Wolf and Bobcat zones.

Exploration Budget for 2018: $100M

Osisko’s 2018 exploration budget for the Windfall/Lynx deposits, Urban Barry and Quévillon project areas totals approximately $100 million. This budget includes resource estimation work, resource-oriented drilling, exploration ramp and underground bulk sampling of known mineralized zones, metallurgical work, permitting, PEA and feasibility studies, exploration drilling proximal to Windfall and Lynx, and exploration drilling on the greater Urban Barry and Quévillon properties.

Windfall/Lynx: Initial Resource Estimation Planned for May 2018, PEA Planned for June 2018

Osisko’s initial resource for Windfall is scheduled to be released in early May, a delay of six weeks from the previous Q1 2018 estimated completion, due to the slower than anticipated turnaround of assay data. Osisko plans to have a Preliminary Economic Assessment completed in June 2018 for the Windfall deposit subsequent to the release of the initial resource estimate.

The main Windfall deposit and the Lynx deposit (discovered by Osisko in early 2017) remain open to the NE and at depth, and surface exploration drilling is continuing. Newly discovered extensions of the main Windfall deposit (Caribou Extension, Zone 27 Extension, Underdog Expansion), and part of the Lynx deposit and its sub zones below 350 metres depth and further northeast of section 3750E, will not be included in the May 2018 resource estimate, due to lack of adequate drill density. Infill drilling planned for the balance of 2018 will be focused on these areas, with the aim of including them in a planned Q1 2019 feasibility study.

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